Investigations will be continued on the mechanisms of action of ethanolamine ammonia-lyase, an adenosylcobalamin-dependent enzyme. The action of the enzyme on ethanolamine analogs will be studied, directing particular attention to the possibility that 1-amino-2-propanol is a substrate. The investigation of the stereochemistry of the reaction will be continued. Other mechanistic studies will include an investigation of the reaction by ESR spectrometry using isotopically labelled ethanolamine, and an investigation of the unusually high tritium isotope effect which characterizes the transfer of hydrogen from cofactor to product. Finally, attempts will be made to tag the active site with affinity labels.